[Research and development of pravastatin]

Comparison of simvastatin 1.2% gel and alendronate 1% gel in chronic periodontitis as local drug delivery: A randomized clinical trial

Introduction

Simvastatin (SMV) is used for the treatment of hypercholesterolemia. Long-term systemic administration of SMV has been shown to result in increased bone mineral density. Alendronate (ALN) is known to inhibit osteoclastic bone resorption and has osteostimulative properties.

Aim

To compare percentile changes in gain in clinical attachment level and reduction of pocket depth, and to radiographically evaluate osseous defect fill with subgingival local drug delivery of 1.2% SMV gel and 1% ALN gel.

Materials and Methods

A split-mouth study was conducted with 40 infrabony defects from 20 patients diagnosed with chronic periodontitis. The sites were assigned as test site 1 (SMV gel) or test site 2 (ALN gel). After phase I therapy, a single application of SMV gel or ALN gel was done into periodontal pockets. Clinical periodontal parameters and percentage of bone fill were evaluated at baseline, 3 and 6 months.

Results

There was a statistically significant reduction in pocket depth, plaque index, and bleeding index scores, gain in Clinical attachment level (CAL) and bone defect fill from baseline to 6 months at both sites. On comparison between the groups, test site 2 showed significant improvement in clinical attachment level than in test site 1 at 6-month follow-up. Test site 2 showed more percentage bone fill than test site 1.

Conclusion

Usage of both SMV and ALN gels in periodontal intra bony defects can lead to significant improvements in clinical and radiographic parameters; however, ALN showed better osseous defect fill.

Bone regeneration by statin and low-intensity pulsed ultrasound (LIPUS) in rabbit nasal bone

OBJECTIVES

To compare bone regeneration between local implantation of statin and low-intensity pulsed ultrasound (LIPUS), and the combination of statin with LIPUS in rabbit nasal bone using histological and immunohistochemical methods.

STUDY DESIGN

Thirty-two adult male Japanese white rabbits (age: 12-16 weeks, weight: 2.5-3.0 kg) were used in this study. Two bone circular defects (5 mm in diameter) per rabbit were created in the nasal bone while preserving the nasal membrane. The two defects in each rabbit were filled with 2.5 mg/ml simvastatin in 0.2 ml water with an atelocollagen sponge (ACS) and ACS alone respectively. Sixteen rabbits (32 sides) received the LIPUS application; the remaining 16 rabbits (32 sides) did not. Therefore, the subjects composed of 4 groups, namely, (1) LIPUS + ACS + simvastatin (the LAS group), (2) LIPUS + ACS (the LA group), (3) ACS + simvastatin (the AS group) and (4) ACS alone (the A group). Four animals were killed in each period, at 1, 2, 4 and 8 weeks postoperative. The parts that had been operated on were removed and prepared for histological assessment. The expression of BMP-2 and the bone area ratio were evaluated using histological and immunohistochemical methods.

RESULTS

Bone square in the LAS group was significantly larger than that in the AS group after 1 (P < 0.0001) and 2 week (P = 0.0113). The bone square in the LA group was significantly larger than that in the A group after 1 (P < 0.0001) and 2 weeks (P = 0.0090). However, there was no significant difference between the LAS and LA groups. In the number of cells that stained positive for BMP-2, the LAS group was significantly larger than that in the AS group after 1 (P < 0.0001) and 2 weeks (P = 0.0113).

CONCLUSION

This study suggests that bone regeneration can be promoted by LIPUS alone and statin alone, respectively. However the combination use of LIPUS with statin does not differ from LIPUS alone or statin alone.

Statins: A new era in local drug delivery

Periodontitis is an inflammatory disease of the supporting tissues of the teeth, caused by a group of specific microorganisms. Aggressive forms of periodontitis can be localized or generalized. The concept that localized problem sites may be treated by local drug delivery appears attractive as the antimicrobial agent is delivered within periodontal pockets and the therapy is targeted on specific pathogenic microorganisms. Periodontitis can result in bone resorption creating bony defects, which may cause tooth loss. Various drugs have been studied using local delivery to improve the periodontal health and to achieve periodontal regeneration. Local delivery of antimicrobial agents using controlled release systems should be considered as adjunctive to mechanical debridement for the treatment of localized forms of periodontal destruction. Pharmacological agents offer great promise in this direction. Simvastatin, used for the treatment of hypercholesterolemia, is a universally accepted and relatively inexpensive drug. Local application of simvastatin has been shown to stimulate bone formation in rodents both in vitro and in vivo and in human periodontal ligament cells in vitro. This article reviews the effects of simvastatin as a local delivery and examines its potential role in periodontal regenerative therapy.

Bone healing of critical-sized nasal defects in rabbits by statins in two different carriers

OBJECTIVES

To evaluate bone healing following implantation of a statin with two different carriers in rabbit nasal bone using histological and immunohistochemical methods.

MATERIALS AND METHODS

Twenty adult, male Japanese white rabbits (age: 12-16 weeks, weight: 2.5-3 kg) were used in this study. Five bone circular defects (5 mm in diameter) per rabbit were created in the nasal bone while preserving the nasal membrane. In the experimental groups, 2.5 mg/ml simvastatin dissolved in 0.2 ml water with hydrogel was implanted in one group, 2.5 mg/ml simvastatin dissolved in 0.2 ml water with an atelocollagen sponge (ACS) in the second group with, only the hydrogel in the third group and only an ACS in the fourth group. No material was implanted in the control group. Four animals were killed in each period, at 1, 2, 4, 8 and 12 weeks postoperatively. The parts that had been operated on were removed and prepared for histological assessment. The expression of bone morphogenetic proteins (BMP)-2 and the bone ration was evaluated using histological and immunohistochemical methods.

RESULTS

No significant differences were observed between the simvastatin with hydrogel group and the simvastatin with ACS group at 1, 2, 4, 8 and 12 weeks postoperatively regarding expression of BMP-2, although the number of cells that stained positive for BMP-2 in both of the implanted groups increased significantly at 2 and 4 weeks postoperatively in comparison with the control group (P<0.0001). For new bone area ratio, there were no significant differences between the simvastatin with hydrogel groups and the simvastatin with ACS group after 2, 4, 8 and 12 weeks, although these groups showed higher value than control group (P<0.0001).

CONCLUSION

This study suggests that both the simvastatin with hydrogel and simvastatin with ACS implants showed similar BMP-2 expression and new bone formation, and there were no significant differences between the two carriers.

Clinical effect of subgingivally delivered simvastatin in the treatment of patients with chronic periodontitis: a randomized clinical trial

BACKGROUND

Periodontitis is an inflammatory disease that results in bone resorption creating bony defects, which may cause tooth loss. Various drugs have been studied using local delivery to improve the periodontal health and to achieve periodontal regeneration. Simvastatin (SMV) is a specific competitive inhibitor of 3-hydroxy-2-methyl-glutaryl coenzyme A reductase. The present study was designed to investigate the effectiveness of SMV, 1.2 mg, in an indigenously prepared biodegradable controlled-release gel as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis.

METHODS

Sixty patients were categorized into two treatment groups: SRP plus placebo (group 1) and SRP plus SMV, 1.2 mg (group 2). Clinical parameters were recorded at baseline before SRP and at 1, 2, 4, and 6 months; they included modified sulcus bleeding index (mSBI), probing depth (PD), and clinical attachment level (CAL). At baseline and after 6 months, radiologic assessment of intrabony defect (IBD) fill was done using computer-aided software. The mean concentration of SMV in gingival crevicular fluid was estimated by reverse-phase high-performance liquid chromatography.

RESULTS

All subjects tolerated the drug, without any postapplication inflammation. Both therapies resulted in significant improvements. The decrease in mSBI score at 6 months was greater in group 2 (2.3267 +/- 0.8017) compared to group 1 (0.5033 +/- 0.6815). The mean decrease in PD from baseline to 6 months was 1.20 +/- 1.24 mm and 4.26 +/- 1.59 mm in groups 1 and 2, respectively. Mean CAL gain from baseline to 6 months was 1.63 +/- 1.99 mm and 4.36 +/- 1.92 mm in groups 1 and 2, respectively. In group 2, there was greater decrease in mean IBD (1.41 +/- 0.74 mm or 32.54%) compared to group 1 (0.09 +/- 0.58 mm or 2.16%).

CONCLUSION

There was a greater decrease in gingival index and PD and more CAL gain with significant IBD fill at sites treated with SRP plus locally delivered SMV in patients with chronic periodontitis.

Statin-induced bone morphogenetic protein (BMP) 2 expression during bone regeneration: an immunohistochemical study

OBJECTIVES

The purpose of this study was to investigate bone morphogenetic protein (BMP) 2 expression after implantation of a statin and recombinant human BMP-2 (rhBMP-2) and to compare the bone regeneration capability of these substances in the rabbit nasal bone using immunohistologic methods.

STUDY DESIGN

Twelve adult male Japanese white rabbits (n = 12; age 12-16 weeks, weight 2.5-3.0 kg) were divided into 3 experimental groups and 1 control group. A total of 48 bone defects, 4 per rabbit, were created in the nasal bone while preserving the nasal membrane. In the experimental groups, 1 group was implanted with 10 mg of a statin dissolved in 0.2 mL water with an atelocollagen sponge (ACS); the second group was implanted with 5 microg rhBMP-2 with an ACS; and in the third group only the ACS was implanted. No material was implanted in the control group. Animals were killed at 1, 2, and 4 weeks after surgery. The parts that had been operated on were removed and prepared for histologic assessment. The expression of BMP-2 was evaluated using immunohistochemistry, and double-immunostaining for BMP-2 and Ki-67 was observed by fluorescent microscopy.

RESULTS

No significant differences were observed between the statin/ACS group and rhBMP-2/ACS group at 1, 2, and 4 weeks after surgery. The number of cells which stained positively for BMP-2 increased significantly in both of the implanted groups compared with the control group (P < .0001). The positive fluorescent double-immunostaining for BMP-2 and Ki-67 was similar in both implanted groups.

CONCLUSION

This study suggests that statin/ACS implants show BMP-2 expression and osteoinductive activity that is similar to those of rhBMP-2/ACS implants.

The role of statins as potential targets for bone formation

Inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A reductase enzyme have recently been shown to stimulate bone formation in rodents both in vitro and in vivo. In bone cells, these inhibitors increase the gene expression of bone morphogenetic protein-2, which is an autocrine-paracrine factor for osteoblast differentiation. The findings that statins increase bone formation and bone mass in rodents suggest a potential new action for these compounds, which may be beneficial in patients with established osteoporosis where marked bone loss has occurred. Recent clinical data suggest that they may reduce the risk of fracture in patients taking these drugs.

Development and progression of atherosclerosis in aorta from heterozygous and homozygous WHHL rabbits. Effects of simvastatin treatment

This study was conducted to define progression of atherosclerosis in both homozygous and heterozygous Watanabe heritable hyperlipidemic (WHHL) rabbits and to investigate the ability of the HMG CoA reductase inhibitor simvastatin to attenuate progression of the disease. We examined contractile responses to phenylephrine and endothelium-dependent relaxation in response to carbachol in thoracic aorta at 3, 6, 9, and 12 months in control New Zealand White (NZW) rabbits, homozygous WHHL rabbits, and heterozygous WHHL rabbits. Homozygous and heterozygous rabbits were treated with simvastatin (10 mg/kg per day) from 3 to 6 months and from 9 to 12 months of age. Simvastatin significantly reduced serum cholesterol levels in young heterozygotes, with a nonsignificant trend toward a reduction in older heterozygotes. In homozygotes, no significant fall was observed. Contractile function declined progressively with age in all groups--most in homozygotes and least in NZW rabbits. Relaxation was unaffected by age in NZW rabbits; relaxation declined in the heterozygotes and declined to a greater extent in homozygotes. Simvastatin retarded the loss of function in the young heterozygotes. Similar trends were observed in young homozygotes and older heterozygotes, with no effect in older homozygotes. Histological studies revealed the progressive development of early atherosclerosis in heterozygotes, and more advanced atherosclerosis was observed in homozygotes. Simvastatin did not inhibit development of atheroma. A correlation was observed between vascular function and structure. However, functional changes preceded the development of atheroma. In addition, we have demonstrated that simvastatin can help to reduce the loss of vascular function associated with the progression of atherosclerosis in the heterozygous WHHL rabbit.